Beverage preparation machines are well known in the food science and consumer goods area. Such machines allow a consumer to prepare at home a given type of beverage, for instance a coffee-based beverage, e.g. an espresso or a brew-like coffee cup.
Today, most beverage preparation machines for in-home beverage preparation comprise a system made of a machine which can accommodate portioned ingredients for the preparation of the beverage. Such portions can be soft pods or pads, or sachets, but more and more systems use semi-rigid or rigid portions such as rigid pods or capsules. In the following, it will be considered that the beverage machine of the invention is a beverage preparation machine working a semi-rigid or rigid capsule.
The machine comprises a receptacle for accommodating said capsule and a fluid injection system for injecting a fluid, preferably water, under pressure into said capsule. Water injected under pressure in the capsule, for the preparation of a coffee beverage according to the present invention, is preferably hot, that is to say at a temperature above 70° C. However, in some particular instances, it might also be at ambient temperature. The pressure inside the capsule chamber during extraction and/or dissolution of the capsule contents is typically about 1 to 6 bar for dissolution products, 2 to 12 bar for extraction of roast and ground coffee. Such a preparation process differs a lot from the so-called “brewing” process of beverage preparation—particularly for tea and coffee, in that brewing involves a long time of infusion of the ingredient by a fluid (e.g. hot water), whereas the beverage preparation process allows a consumer to prepare a beverage, for instance coffee within a few seconds.
The principle of extracting, infusing, and/or dissolving the contents of a closed capsule under pressure is known and consists typically of confining the capsule in a receptacle of a machine, injecting a quantity of pressurized water into the capsule, generally after piercing a face of the capsule with a piercing injection element such as a fluid injection needle mounted on the machine, so as to create a pressurized environment inside the capsule either to extract the substance or dissolve it, and then release the extracted substance or the dissolved substance through the capsule. Capsules allowing the application of this principle have already been described for example in applicant's European patent no EP 1 472 156 B1, and in EP 1 784 344 B1.
Machines allowing the application of this principle have already been described for example in patents CH 605 293 and EP 242 556. According to these documents, the machine comprises a receptacle for the capsule and a perforation and injection element made in the form of a hollow needle comprising in its distal region one or more liquid injection orifices. The needle has a dual function in that it opens the top portion of the capsule on the one hand, and that it forms the water inlet channel into the capsule on the other hand. In many instances, the capsule is inserted into a capsule holder, which is preferably (but not necessarily) detachable from the machine. The capsule holder loaded with the capsule is then inserted into the machine. Using a capsule holder for loading the capsule into the machine is not mandatory though, as the capsule can also be loaded directly into an opening
The machine further comprises a fluid tank—in most cases this fluid is water—for storing the fluid that is used to dissolve and/or infuse and/or extract under pressure the ingredient(s) contained in the capsule. The machine comprises a heating element such as a boiler or a heat exchanger, which is able to warm up the water used therein to working temperatures (classically temperatures up to 80-90° C.). Finally, the machine comprises a pump element for circulating the water from the tank to the capsule, optionally though the heating element. The way the water circulates within the machine is selected via a selecting valve means, such as for instance a peristaltic valve of the type described in applicant's European patent application EP 2162653 A1.
When the beverage to be prepared is coffee, one interesting way to prepare the said coffee is to provide the consumer with a capsule containing roast and ground coffee powder, which is to be extracted with hot water injected therein.
Capsules have been developed for such an application, which are described and claimed in applicant's European patent EP 1 784 344 B1, or in European patent application EP 2 062 831.
In short, such capsules comprise typically:                a hollow body and an injection wall which is impermeable to liquids and to air and which is attached to the body and adapted to be punctured by e.g. an injection needle of the machine,        a chamber containing a bed of roast and ground coffee to be extracted,        an aluminum membrane disposed at the bottom end of the capsule, closing the said capsule, for retaining the internal pressure in the chamber, the said membrane being associated with piercing means for piercing dispensing holes in the said aluminum membrane when said internal pressure inside the chamber reaches a certain predetermined value,        optionally, means configured to break the jet of fluid so as to reduce the speed of the jet of fluid injected into the capsule and distribute the fluid across the bed of substance at a reduced speed.        
Beverage preparation machines and capsules as described above, for many of them, are designed to give the consumer the choice of preparing the beverage he likes amongst a whole range of beverage products.
For each beverage type, the dose of ingredients contained in a capsule are carefully dosed, to correspond to a volume to be dispensed in the cup. Such a volume is optimized to guarantee an optimal organoleptic profile, in terms of flavors, aromas, and texture.
Some machines are automatically set by recognition of the capsule type, so that the machine adapts the volume of beverage that is dispensed in the cup, depending on the beverage that is prepared. Other machines can be programmed manually, so that the user can chose a small cup or a large cup dispensing, whatever the beverage type.
However, such machines have the disadvantage that they lack flexibility to give an easy access to the volume selection at each serve: automated machines do not give any possibility to the consumer to divert from the pre-programmed dispensing volume, and the programmable machines require to be re-programmed each time the user wants to adapt the cup size.